Process for controlling or regulating the basis weight of a paper or cardboard web

Abstract

Device and process for controlling or regulating a basis weight of a web in a web manufacturing process of a web producing machine. The device includes a first control circuit, adapted to adjust the basis weight, that includes at least one adjustable device for influencing the basis weight and at least one basis weight sensor. A second control circuit having at least one sensor for detecting a concentration of incoming backwater is also provided. The process includes measuring the basis weight of the material web, adjusting the basis weight of the web with a first control device having at least one device for influencing the basis weight, detecting a retention change in a second control circuit, and counteracting the retention change by influencing a concentration of a stock suspension placed one of onto a wire and between wires.

What is claimed:  
     
       1. A process for controlling or regulating a basis weight of a material web in a manufacturing process, comprising: 
       measuring the basis weight of the material web;  
       adjusting the basis weight of the web with a first control device having at least one device for influencing the basis weight;  
       detecting a retention change in a second control circuit;  
       counteracting the retention change by influencing a concentration of a stock suspension placed one of onto a wire and between wires.  
     
     
       2. The process according to  claim 1 , wherein the detection of the retention change is made by measuring the incoming backwater. 
     
     
       3. The process according to  claim 1 , wherein the detection of the retention change is made by measuring a concentration of incoming backwater. 
     
     
       4. The process according to  claim 1 , wherein the detection of the retention change is made in incoming backwater before a backwater container. 
     
     
       5. The process according to  claim 1 , wherein the detection of the retention change is made in backwater of a headbox supply. 
     
     
       6. The process according to  claim 1 , wherein the second control circuit is subordinate to the first control circuit. 
     
     
       7. The process according to  claim 1 , wherein the first control circuit includes actuators coupled to the at least one device for influencing the basis weight, and the second control circuit is coupled to the actuators. 
     
     
       8. The process according to  claim 1 , wherein when a reduction in retention is detected, the process further includes increasing a concentration of a stock suspension supplied to a headbox. 
     
     
       9. The process according to  claim 1 , wherein when an increase in retention is detected, the process further includes reducing a concentration of a stock suspension supplied to a headbox. 
     
     
       10. The process according to  claim 1 , wherein when a decrease in retention is detected, the process further includes supplying a retention agent. 
     
     
       11. The process according to  claim 10 , wherein the retention agent is a concentrated retention agent. 
     
     
       12. The process according to  claim 1 , wherein when an increase in retention is detected, the process further comprises reducing a supply of retention agent. 
     
     
       13. The process according to  claim 1 , further comprising regulating a backwater-regulated headbox that is sectioned across a width of the machine. 
     
     
       14. The process according to  claim 1 , wherein the at least one basis weight measurement is made in a vicinity of a drying section. 
     
     
       15. The process according to  claim 14 , wherein the at least one basis weight measurement is made at an end of the drying section. 
     
     
       16. The process according to  claim 1 , wherein the at least one basis weight measurement is made in a vicinity between a press section and a drying section. 
     
     
       17. The process according to  claim 16 , wherein the at least one basis weight measurement is made at an end of the press section. 
     
     
       18. The process according to  claim 1 , wherein the material web comprises one of a paper and cardboard web. 
     
     
       19. A process for controlling or regulating a basis weight of a web in a web manufacturing process of a web producing machine, comprising: 
       measuring a basis weight of the web;  
       controlling at least one adjustment device with a first control circuit in accordance with the measured basis weight to adjust the basis weight of the web;  
       detecting a concentration of incoming backwater; and  
       adjusting the basis weight with a second control circuit in accordance with the detected concentration.  
     
     
       20. The process according to  claim 19 , wherein the machine includes a headbox having a stock inlet and a backwater supply coupled to the stock inlet, and the process further comprises: 
       adjusting the backwater supply via the at least one adjustment element is coupled to said backwater supply,  
       wherein said second control circuit is also coupled to the at least one adjustment device.  
     
     
       21. The process according to  claim 20 , wherein the at least one adjustment element includes a backwater adjustment element and a stock adjustment element, and the process further comprises: 
       adjusting the backwater adjustment element via at least one of the first and second control circuits; and  
       adjusting the stock adjustment element via at least one of the first and second control circuits.  
     
     
       22. The process according to  claim 19 , wherein the machine includes a headbox having a stock inlet with a stock inlet control, and a backwater supply coupled to said stock inlet with a backwater supply control, the process further comprises: 
       adjusting the stock inlet via the at least one adjustment element; and  
       adjusting the backwater supply control and the stock inlet control via the second control circuit.  
     
     
       23. The process according to  claim 19 , wherein the machine includes a headbox having a stock inlet having a first stock inlet adjustment element and a second stock inlet adjustment element, and a backwater supply coupled to said stock inlet, the process further comprises: 
       adjusting the backwater supply with the at least one adjustment element;  
       adjusting the second stock inlet adjustment element with the first control circuit; and  
       adjusting the first stock inlet adjustment element and the at least one adjustment device with the second control circuit.